Cardiac remodeling from obesity and hypertension starts early.

Obesity throughout life was more strongly associated with the development of left ventricular hypertrophy (LVH) than was blood pressure (BP), according to an analysis of data from the long-running Bogalusa Heart Study.

Regression coefficients of body mass index (BMI), which were 0.26 in childhood and 0.42 in adulthood, were greater than the regression coefficients of systolic BP for left ventricular mass index (LVMI), which were 0.08 in childhood and 0.16 in adulthood, according to Gerald S. Berenson, MD, of Tulane University in New Orleans, and colleagues.

In addition, odds ratios of LVH were greater for BMI, at 1.65 (95% CI 1.39-1.97) in childhood and 2.53 (95% CI 2.06-3.09) in adulthood, compared with odds ratios for systolic BP of 1.27 (95% CI 1.04-1.54) and 1.56 (95% CI 1.28-1.90), the researchers reported in the Oct. 14 Journal of the American College of Cardiology.

Previous Bogalusa study findings suggested that both childhood BMI and blood pressure predict adult LVH, but details such as the the relationship of these cardiovascular risk factors on left ventricular geometric remodeling patterns have not been previously reported.

"By taking advantage of the longitudinal cohort of the Bogalusa Heart Study followed up from childhood, we found that the influence of adiposity measures and blood pressure levels began in early life," the researchers wrote.

Study Details

The current study involved 1,061 adult participants who were followed as preschool and school-age children for close to 4 decades in the town of Bogalusa, La. Between 1973 and 2010, nine cross-sectional surveys of children and 10 cross-sectional surveys of adults who had enrolled as children were conducted, providing serial data every 2 to 3 years.

The study population included 717 whites and 344 blacks whose ages ranged from 24 to 46. A total of 42.6% were men, and mean follow-up was 28 years. They had undergone measurements of left ventricular dimensions at least twice as children and again as adults.

The overall burden of BMI and BP was assessed as the area under the curve (AUC), with total AUC representing the cumulative burden and incremental AUC representing longitudinal trends without considering baseline levels.

The effects of BMI and systolic BP on LVH and LVMI in adult life were assessed on regression analyses, using four values of BMI -- childhood, adulthood, total AUC, and incremental AUC, adjusting for sex, race, and adult age. Significant associations were seen for all, but the linear regression model determined that the effects of BMI were stronger than the effects of BP.

The researchers then looked at patterns of left ventricular geometry, and defined these four:

Normal: normal relative wall thickness with no LVH

Concentric remodeling: increased wall thickness without LVH

Eccentric hypertrophy: normal wall thickness with LVH

Concentric hypertrophy: increased wall thickness with LVH

The overall rates of these patterns were 10.2% for eccentric hypertrophy, 9.1% for concentric remodeling, and 4.2% for concentric hypertrophy.

Geometric patterns differed by race, with blacks more commonly having eccentric hypertrophy (17.8% versus 8.95%, P<0.001) and concentric hypertrophy (9.1% versus 3.6%, P<0.001) compared with whites. The prevalence of concentric remodeling was similar in blacks and whites (10.1% and 10.9%).

Additional analysis determined that all BMI values were more strongly associated with eccentric hypertrophy. "Importantly, this study provides strong evidence that, compared with blood pressure, BMI is more closely and consistently associated with eccentric hypertrophy using childhood, adulthood, and AUC values," the researchers wrote.

Collaborative Data, New Insights

In an accompanying editorial, Sheldon E. Litwin, MD, of the Medical University of South Carolina in Charleston, wrote that measuring the evolution of organ damage from childhood to adulthood remains a challenge, but that the methodological tools used by the Bogalusa Heart Study researchers "should prove valuable for quantifying the cumulative burden of any risk factor or combination of risk factors over time in longitudinal studies."

The finding that BMI is a stronger predictor of eccentric hypertrophy in adults than blood pressure differs from several other recent studies, he noted.

"Conventional thinking has held that hypertension produces concentric hypertrophy, whereas obesity is predominantly associated with eccentric hypertrophy," possibly because of volume load on the heart.

"Contrary to this standard of thinking, several recent large-scale, cross-sectional studies have shown that obese adults most often had concentric, not eccentric, LV geometry," he wrote.

"This type of collaborative effort is highly commendable and likely to yield extraordinary new knowledge that will benefit the global health community in understanding the effects of childhood obesity," Litwin wrote. "Although we eagerly await the insights that will emerge from the collaboration, we cannot forestall embarking on the monumental effort that will be required to find methods to control or, better yet, prevent the growing crisis of childhood obesity."

Berenson and colleagues concluded, "These observations suggest that the process of LV enlargement and subclinical changes in cardiac structure are affected by a life course of excessive adiposity and blood pressure cumulatively and independently from early life, through multiple complex pathophysiological and metabolic mechanisms."

They noted that the exclusion of patients on blood pressure medications was a potential limitation of the analysis.

The study was funded by the National Institute of Environmental Health Science, the National Institute on Aging, and the American Heart Association.

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